Electric elevator system.



E. M. FRASER;

ELECTRIC ELEVATOR SYSTEM.

APPLICATION FILED JULY 29, 1912.

' 1,093,583. Patented Apr. 14, 1914.

2 SHEITSSHEBT l.

@311 affozucl s E. M. FRASER.

ELECTRIC ELEVATOR SYSTEM.

APPLICATION FILED JULY 29, 1912.

1,093,583. Patented Apr. 14, 1914.

2 SHEETS-SHEET 2.

MOTORV8 MOTOR 20 UNITED srra'i ss Parana. OFFICE.

ETHELTBERT M. FRASER, OF YONKERS, NEV YORK, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO GENERAL ELEVATOR COMPANY, OF JERSEY- CITY, NEW JERSEY, A

CORPORATION OF NEW JERSEY.

ELECTRIC ELEVATOR SYSTEM.

Specification of Letters Patent.

Patented Apr. 14, 1914.

Application filed July 29, 1912. Serial No. 711,957. R I

- Systems, 0 which the following is a specification.

In its broadest aspects, my improved electric elevator system or hoisting apparatus, which is of the tract-ion type, comprises two independently-operated pulleys or driving members arranged to rotate about the same axis or parallel axes, an idler pulley or sheave, and power-transmitting means.

In one embodiment of my invention, my improved electric elevator system comprises two shunt-wound electric motors, whose armature shafts are in alinement and coupled rigidly together so as to revolve in unison and Whose field structures are mounted so as to rotate independently of each other in opposite directions, each field structure carrying a pulley ,or sheave, an idler pulley or sheave, and a flexible connector passing over and engaging said pulleys or sheaves, one end of the connector being connected to the car and the other end to a counterweight.

One of the objects of my invention is to provide an electric elevator system, comprising two electric motors or dynamos whose armatures are mechanically connected together and-having rotatable field magnets, in which the elevator'car is controlled by varying the field strength of either or both motors.

Another object is to provide an electric elevator system in which the power-operating instrumentalities will oppose each other, thereby constituting an electric lock or brake to hold the car from descending or ascending.

Another object is to provide an electric traction elevator system or hoisting apparatus, comprising two electric motors or dynamos having rotatable field magnets and armatures, in which the power-transmitting means is driven by two independently-operated pulleys or sheaves connected to the field structures rotating in opposite directions.

Another object is to provide an electric elevatorsystem in which there are no sudden rushes of current from or into the line when the car is started or stopped.

lith the above and other objects in View, my invention consists of the construction, arrangements and combinations of parts hereinafter described and claimed.

An electric elevator or hoisting system embodying the features of my invention is illustrated in the accompanying drawings, forming a part of this specification, in which Figure 1 is a view illustrating diagrammatically the arrangement of the independently-operated pulleys or sheaves, the-idler pulley or sheave, and the power-transmitting means connected to the car and counterweight. Fig. 2 is a view partly in section of the operating motors, the idler pulley or sheave. and the power-transmitting means. Fig. 3 is a wiring diagram.

In the drawings, similar figures of refer ence refer to similar parts throughout the several views.

As shown in Fig. 1, my improved electric elevator or hoisting system comprises the two independently operated pulleys or sheaves 10 and 11 preferably arranged to rotate about the same axis or shaft 12, the idler pulley or sheave 13, and the power-transmitting means 14. In the embodiment of my invention as shown, the power-transmitting means 14 are connected to the car 15, and the counterweight 16. Being merely diagrammatic, no bearings for the different rotating elements are shown in Fig. 1, this feature being shown in detail in Fig. 2.

Referring to Fi ..2, the pulley or sheave 10 forms a part 0' or is secured to the -field structure 17 of the motor 18, and the pulley or sheave 11 forms a part of or is secured to the field structure 19 of the motor 20. The motors 18 and 20, which are of the standard shunt-wound type, comprise the field structures 17 19, the armatures 21, 22, and the commutators 26, 26, respectively. The armature shafts 12, 12 are preferably in alinement and rigidly secured together by the coupling 23, or, a unitary armature shaft may be used for the two motors. The armature shafts 12, 12 are suitably supported in bearings 24, 2 1 to permit of the shafts and armatures 21, 22 revolving in unison. The field structures 17, 19, are also suitably supported in bearings 25, 25 to permit of the field structures rotating independently of each other and of the armatures in either direction. If desired, a fly-wheel 27 may be mounted on the shaft of the armatures for the purpose of storing up and giving out power, thereby causing the flow of current from the main source of supply to be more uniform and reducing the sudden rushes of current when starting or stopping the elevator. The idler pulley or sheave. 13 is suitably supported in the hanger 28 and arranged so as to rotate freely in either direction. The power-trans mitting means preferably comprise a plurality of iron hoisting ropes 14 which engage grooves 28, 28 in the pulleys or sheaves 10, 11 and 13, the ropes losing connected at one end to the car 15 and at the other end to the counterweight 16. As will be shown hereinafter, it is not necessary to provide a fric- 'tion brake to control the movement of the car, as the two motors under certain conditions constitute an electric loclrin device to hold the car from ascending or escending. In case, however, there should he a cessation in the current supply, means are provided for holding the field structures of the motors from rotating thereby preventing the car from ascending or descending, or f preferred, means for gripping the hoisting ropes may be used.

As shown in Fig. 3, the field magnets of the motors 18 and 20 are electrically connected up in series and connected across the line or power mains 30 and 31, while the armatures 21, 22 are in multiple and connected across the line. The system is also provided with the usual armature starting rheostat 34, a suitable fixed resistance 32 in the field circuits, and a plain field rheostat 33 to vary the field strength of either motor. In the embodiment of my invention as illustrated the rheostat 33 1s placed in the elevator car.

The method of operation is as follows: The armatures are started up and rotate clockwise as indicated by the arrows (Fig. 1) 'at say 500 revolutions per minute, while the field structures remain stationary. For the purpose of illustration, the field magnet is considered to be rotating in the plus direction when rotating opposite to its armature, and in the minus direction when it' rotates in the same direction as its armature, the algebraic sum of the speeds of the armature and field magnet beingthe effective speed of the armature. If the field magnet does not rotate, the speed rt the armature will be the effective speed. If there is a load on the car, and the weight of the car and load is in excess of that of the counterweight, the natural tendency would be for the car and load to descend,

meat-pea rotated in the same direction as its armature 21,.the effect being to make this part of the apparatus act as a motor and take current from the line. The ultimate effect of the armature 22 sending current into the line and the armature 21 taking current from the line is to prevent the field structures 17, 19, from rotating, thereby holding the car and load from descending. That is, the arrangement of having both arn1atures connected to the line and the field magnets of the two motors of the same strength constitutes an electric locking device.

When it is desired to raise the car and load (it is assumed that the armatures are running at the maximum speed of 500 revolutions per minute when the car is at rest), field strength of motor 20 is strengthened sulliciently, for example, to make the ef fective speed 400 revolutions per minute. As the armature shafts of the two motors are connected together, in order to permit armature 22 to slow up it would be necessary to lower the speed of armature 21. As the field structure strength of motor 18 has not been changed, armature 21 opposes the slowing up effect of armature 22. Armature 20 not being able to slow up and field structure 19 being free to rotate, the latter will turn in the same direction as the armature or in a minus direction, the efiect being the same as if the armature 20 were slowed up. I

As the field structures 1?, 19, are connected by the hoisting ropes 14, one cannotrotate without the other, and as field structure 19' rotates in the minus direction the field structure 17 will rotate at the same speed in the plus direction. The field strength of motor 18 remaining the same and field structure 17 rotating in the plus direction, armature 21 will slow up the same number of revolutions as the field structure 17 turns in the plus direction. The final efiect of strengthening the field magnets of motor 20 to get an effective armaturefspeed of 4:00 revolutions per minute and keeping the field strength of motor 18 constant to get an effective armature speed of 500 revolutions per minute is to cause the armatures 21, 22 to slow up to 450 revolutions per minute, the field structure 19 to rotatev 50 revolutions per minute in the minus direction and. the field structure 17 to rotate 5O revolutions per minute in the plus direction.

Whenever it is desired to stop the elevator car, the field strength of motor 20 is weakened to the original density or its field strength is made the same as that of motor 18,thereby preventing the field structures from rotating and efiectually locking or braking the car. g

4 In order to lower the car, the field strength of motor 18 is increased and the field strength of motor 20 is maintained at the normal density, the action being the same as momentum of the armatures and fly-wheel is used to help start the car and counterweight from a state of rest, and it is taken up in increasing the speed of the armatures and fly-wheel.

The ultimate effect is to prevent sudden rushes of current from or 1nto the line when starting or stopping the car. These sudden rushes of current have been one of the greatest defects of electric elevators, especially where a number of elevators have been operated in ban-c from an isolated plant.

'As. it is possible to operate the system with armatures running at a constant speed, the normal speed will be the average speed, and as the field strength of one motor is weakened the field strength of the other motor is increased inexact proportion. v

It will be obvious that numerous emissions, substitutions and changes may be made in the various parts, arrangements and wiring herein shown and described w thout, however, departing from my invention. It is to be further understood that I do not wish to be limited to the specific featuresof construction and arrangement of parts, or to the specific application of my invention, herein set forth.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In an electric elevator system, the combination with two electric motors having rotatable armatures and field structures rotatable in opposite directions of a plurality of pulleys, two of said pulleys being secured to and driven by said field structures, and

' power-transmitting means engaging said pulleys.

2. In an electric elevator system, the combination with two electric motors having their armatures mechanically coupled together and their field structures rotatable in opposite directions, of means for varying the field strength of either or both of said motors, and power transmitting means driven by said field structures.

3. In an electric elevator system, the combination with a car, of a counterweight, two

electric motors having rotatable field structures and armatures, means for varying the field strength of said motors, a plurality of sheaves, two of said sheaves being operated by said field structures, and power-transmitting means connecting said car and counterweight and engaging said sheaves.

4. The method of operating an electric elevator driven by two electric motors or dynamos, having their armature shafts mechanically connected together and their field magnets rotatable in opposite directions,

-which consists in making the field strength of the two motors or dynamos unequal so that one motor or dynamo will always act as a motor when the other acts as a dynamo, and transmitting the reactive thrust of the armatures on the field magnets to an elevator car and counterweight.

5. The, method of controlling an elevator car driven by two electric motors or dynamos, having their armature shafts mechanically connected together and their field magnets rotatable in opposite directions, which consists in varying the field strength of either or both of said motors or dynamos to control the direction of rotation of said field magnets.

6. In an electric elevator system, the combination with two electric motors having their armatures mechanically coupled together and field structures rotatable in opposite directions, of means for varying the relative speeds and direction of rotation of said field structures, and a flexible connector engaging said field structures.

7. In an electric elevator system, the combination with two electric motors having rotatable armatures and field magnets rotatable in opposite directions, of a sheave or pulley connected to the field magnets of each motor and driven thereby, an independent idler sheave or pulley, and a flexible connector engaging all of said sheaves or pulleys.

8. In an electric elevator system, the combination with two electric motors having armatures mechanically coupled together and independently rotatable field structures,

of a sheave or pulley driven by each of said field structures, an independent idler sheave or pulley, a flexible connector engaging all of said sheaves or pulleys, and means -for controlling the speed and direction of rotation of said field structures.

9, In an electric elevator system, the combination with two electric motors having armatures mechanically coupled together and independently rotatable field structures, of a sheave or pulley carried by each of said field structures and driven thereby, an independent idler sheave or pulley, a flexible connector engaging all of said sheaves or pulleys, and means for varying the field strength of either or both of said motors.

10, The combination with. two electric ino tors having their armatures mechanically coupled together and their field structures rotatable in opposite directions at the same speed, of a pulley or sheave carried by each of said fieldstructures, an independent idler sheave or pulley, a flexible connector engaging all of said pulleys or sheaves, and means for varying the speed and direction of rotation of said field structures.

11. The combination with the power mains or source of current supply, of two electric motors having" rotatable field magnets electrically connected in series across. the power mains, armatures electrically con nected in. multiple across the. power mains and their armature shafts mechanically coupled together, a pulley or sheave carried by the field structure of each motor, an independent idler sheave or pulley and powertransmitting means engaging all. of said pulleys or sheaves and driven by the two firstmentioneol pulleys or sheaves 12. The combination with the power mains or source of current supply of two electric motors having rotatable field magnets electrically connected in series across the power mainsarrnatures electrically connected in multiple across the power mains and their armature shafts mechanically coupled. together, a pulley or sheave driven by the field magnets of each motor an independent idler sheave or pulley, power-transmitting means engaging all of. said pulleys or sheaves and driven by the meanestwo first-mentioned pulleys or sheaves, and means for varying the speed and direction of rotation of said field magnets.

13. In an electric elevator system the combination with a car, of a counterweight, two electric motors having rotatable fields and arnlatures. said armatures being mechanir cally coupled together, means for varying the field strengths of said motors, a pulley driven by each of said fields, an idler pul ley, and a flexible connector connected at one end to said car and passing over one of the pulleys driven by one of said fields to said idler pulley and thence in the opposite direction over the pulley driven by the other of said fields and connected at its other encl'to said counterweight.

14-. The method of operating an electric elevator driven by two electric motors or dynamos having" their armature shafts mechanically connected together and their field magnets rotatable in opposite directions, which consists in transmitting. the reactive thrust of the armatures on the field magnets to an elevator car, and counterweight and making the field strength of the two motors equalto stop the car and varying the field strength of either or both of said motors to move the car up or down.

In testimony whereof, I sign this specification in the presence of two witnesses.

ETHELBERT My FRASER Witnesses Ansrrts B; Bounties Ehvvin' Pecreium 

